Add refresh from source for entries and whole lists

- Every provider can look an entry up again by its ID (TMDB, TheTVDB,
  IGDB, Deezer, MusicBrainz, Wikipedia); search and lookup share parsing
- POST /api/items/{id}/refresh re-applies title, subtitle, year,
  description, link, details and artwork. Kept: the "why" note, rank,
  theater production/venue/cast and a theater entry's year, the Deezer
  preview match. Empty source fields don't erase existing values
- New items.image_custom column (migration 4; existing uploads marked)
  records artwork the owner chose; refresh keeps it unless asked
- Refused for custom lists and hand-added entries; entries the source
  dropped are reported, and a refresh whose title shares no words with
  the current one is rejected as a likely bad ID
- Editor: refresh button per row (asks about the owner's own artwork),
  and "Refresh all" with a confirm step, replace-my-art checkbox,
  progress with Stop, and a summary of problems

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/providers/music_both_test.go

@@ -58,3 +58,21 @@ func TestMatching(t *testing.T) {
 		}
 	}
 }
+
+func TestSameThing(t *testing.T) {
+	for _, c := range []struct {
+		a, b string
+		want bool
+	}{
+		{"Dreams", "Dreams (2004 Remaster)", true},
+		{"DM (old)", "Death Magnetic", false},
+		{"Blonde", "Blond", false},
+		{"Hamilton", "Getting On", false},
+		{"The Legend of Zelda: Breath of the Wild", "Zelda: Breath of the Wild", true},
+		{"", "Anything", true},
+	} {
+		if got := SameThing(c.a, c.b); got != c.want {
+			t.Errorf("SameThing(%q, %q) = %v, want %v", c.a, c.b, got, c.want)
+		}
+	}
+}